If another coalition is needed in 2015, the bottom line for Liberal Democrats must be STV for all subsequent local government elections in England and Wales.

May’s elections changed the political landscape to a four-party one and, if the old two-party First Past The Post (Winner takes All) voting system looked wobbly in a three-party system, it now looks totally discredited in a four-party system.

If each of the largest two parties lacks an overall majority in 2015 but has enough MPs to form a stable coalition with the Liberal Democrats and they both invite the Liberal Democrats to coalition talks, Liberal Democrats have a moral duty to voters to talk first to whichever of the other parties has the more votes even if it has fewer MPs.

If the Conservative Party is persuaded to support PR at all for local government or any other elections, it is likely to want STV. If Liberal Democrats are in talks with Labour about a possible coalition, they should make the same demand. There should be no compromise on this.